Adhesives & Joints (bbcbitesize)

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Design & Technology

Joints

Joints between materials can be either temporary or permanent, and may be formed with adhesives, with frame joints [frame joints: joints in which the components meet at right-angles and fit tightly with each other ], brazed or welded joints, or with fastening components such as nails, screws, bolts, and rivets [rivets: metal or plastic fasteners. The rivet is inserted into holes in the materials to be joined and then end deformed to hold it in place. ].

Types of joint

Joints in wood can be with screws, nails, glues and knock-down [knock-down: joint made up of separate components which are designed to be easily assembled and disassembled ] components, or with frame joints - eg **** joints, halving joints, mortice-and-tenon, dovetail, and box joints.

Joints in metal can be made with brazing [brazing: joining two metal objects by melting a third metal with a lower melting point between them - fusing the two surfaces or edges together. Originally used brass as the 'filler metal' ], soldering [soldering: joining two metal objects by melting a softer metal with a lower melting point between them - thus fusing the two surfaces or edges together. Soldering is a form of brazing ], welding [welding: joining metals by melting and fusing the adjoining edges or surfaces ] or rivets. Joints in plastics can be made with plastic adhesive, rivets, bolts or machine screws.

Most products are made from more than one piece of material, so when the product is assembled or fabricated the pieces need to be joined. Joints can be either permanent or temporary, and there are many different types.

Permanent and temporary joints

Permanent joints are intended to stay put. They may make use of adhesives [adhesives: substances which can bond the surfaces of materials together ], nails, rivets, or one of the heat processes of brazing [brazing: joining two metal objects by melting a third metal with a lower melting point between them - fusing the two surfaces or edges together. Originally used brass as the 'filler metal' ], soldering [soldering: joining two metal objects by melting a softer metal with a lower melting point between them - thus fusing the two surfaces or edges together. Soldering is a form of brazing ] or welding [welding: joining metals by melting and fusing the adjoining edges or surfaces ]. Assembly jigs [jigs: devices for holding parts together while being worked on or assembled ] are often used to hold components in place while they are being joined. For example, the parts of a steel roof frame can be put into the jig and then welded together.

Temporary fixings usually involve components with a screw thread [screw thread: the projecting spiral rib of a screw or bolt ], such as screws, nuts and bolts, or…

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